As global water-related environmental issues intensify, the limitations of conventional wastewater treatment techniques are becoming increasingly evident. Recent contaminants that include heavy metals, organic pollutants, pharmaceuticals, and microplastics are frequently challenging to treat using conventional approaches. This chapter explores the revolutionary ways that nanotechnology and nanomaterials can address these issues. The large surface area, high reactivity, and diverse features of nanomaterials, such as titanium dioxide, graphene oxide, carbon nanotubes, and metal nanoparticles, offer significant benefits. Selective filtering is made possible by graphene oxide, adsorption can be achieved by carbon nanotubes, photocatalytic degradation is facilitated by titanium dioxide, and silver nanoparticles have strong antibacterial properties. The section explores the significant factors, such as pollutant specificity, catalytic efficiency, and adsorption capacity, which influence these materials’ efficacy in treatment wastewater. It also discusses the environmental issues, scaling issues, and useful uses of nanotechnology in the treatment of industrial and municipal wastewater. By resolving these problems, nanotechnology ensures regulatory compliance while opening the door to more economical, effective, and ecologically friendly water treatment options. In the end, nanotechnology offers an effective path toward more efficient and sustainable water treatment techniques that promote environmental stewardship and global water security.